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Studies in the Fat Metabolism of the Timothy Grass Bacillus. 



By Marjory Stephenson, Beit Memorial Besearch Bellow, 

 and Margaret Dampier Whetham. 



(Communicated by Prof. F. G. Hopkins, F.R.S. Received December 14, 1921.) 



(From the Biochemical Laboratory, Cambridge.) 



Studies in fat metabolism have hitherto been chiefly carried out on highly 

 specialised vertebrate tissue. By making investigations on a unicellular 

 organism, more susceptible of laboratory control, two objects were in view : 

 (1) to trace the stages by which the long straight chains of the fatty acid 

 molecules are built up from the constituents of the nutritive medium ; (2) to 

 follow the circumstances and course of their subsequent breakdown. The 

 Timothy grass bacillus was the organism selected, on account of (1) its high 

 content of fat, and (2) its relationsbip to the tubercle bacillus, any facts 

 substantiated by study of the one probably helping to throw light on the 

 chemical habits of the other. 



Methods of Culture and Analysis. 



The medium employed contained inorganic salts in the following pro- 

 portions : — 



Potassium phosphate (K 2 HP0 4 ) 01 grin, per 100 c.c. 



Magnesium sulphate (MgS0 4 -7H 2 0) 0-07 



Ammonium phosphate (Am 3 HP0 4 ) 0'4 „ „ 



Calcium carbonate excess. 



together with traces (about 0'006 grm. per 100 cubic centimetres) of sodium 

 chloride, introduced when the organism was sown. The calcium carbonate was 

 used to maintain the Ph of the medium at a constant value, namely, about 

 8 - 0. The ammonium salt formed the only source of nitrogen. The source of 

 carbon varied with different experiments and will be discussed later ; nothing 

 more complex than glucose was employed. 



Various types of culture vessel were tried, but the only one with which 

 we were able to attain any degree of success was the Boux bottle. Attempts 

 were made to use flasks or large bottles, with rubber stoppers fitted with 

 delivery tubes through which samples of the medium could be withdrawn at 

 intervals. Numerous attempts all proved completely unsuccessful for the 

 following reasons : — (1) The organism grows mainly in a scum on the surface 

 of the medium. If a deep vessel is employed this scum is far removed from 



